opamps used for unity gain

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#21
AD797 does need special care. 100R isolation resistor into inverting input is needed, and feedback lead cap should be less than 30pF. Datasheet have mentioned that.

THS4031 have similar requirement, though it's not writen in the datasheet.

Audio-PCB-2.jpg
 
#24
Hi Guys,
a newbie here. Just wanted to say hello. I saw the comments on amplifiers. FYI, there is a really nice and inexpensive op amp by NJR model NJM4580. It's very fast, extremely low distortion and reasonable power drain. I've designed it into many successful products.
 
#26
Yes, it was designed for Audio. You will find in many Pro Audio devices because of it's price/performance. The last design I did with it, the Audio Precision Portable One, could not measure THD or IMD as it was below it's limits. While that doesn't always make a good sounding audio device, I find them to sound very good, with a very good audio slew rate.
 
#31
SY said:
I suspect not. 😀

I know, I know, it's a dull way to look at things, but wouldn't it be useful if, in subjective evaluation, people stopped talking about a box of gain "sounding good" or "sounding bad," but instead talked about whether or not the output sounded like the input?
Click to expand...

How do you know how the "input" sounds??
Go to the concert hall, listen to the music and compare later ? 🙂
Forget about "sound", I guess we can only measure whatever is measurable and compare numbers.
 
#33
AUDIODH said:
Yes, it was designed for Audio. You will find in many Pro Audio devices because of it's price/performance. The last design I did with it, the Audio Precision Portable One, could not measure THD or IMD as it was below it's limits. While that doesn't always make a good sounding audio device, I find them to sound very good, with a very good audio slew rate.
Click to expand...

Did you design for AP?

Jan
 
#35
audio line or headphone driving I like CFA op amps designed for a/dsl drivers - to use them as unity gain buffers in a composite amp you do need to size the CFA feedback R for unity gain stable operation

and most fast devices will need series output Z to be happy with the C load of cables
 
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#36
jcx said:
audio line or headphone driving I like CFA op amps designed for a/dsl drivers - to use them as unity gain buffers in a composite amp you do need to size the CFA feedback R for unity gain stable operation
Click to expand...

Wouldn't it be so much easier to state you prefer the TPA6120 and recommend what value resistors(if different from the datasheet) to use around it, or show an example of a circuit that you're referring to?🙄

Some CFA op-amps, such as the AD811 for example, do not sound good even when incorporated inside the feedback loop of another op-amp like in the old Jung circuit.
Been there and tried that years ago.

The TPA6120 sounds pretty good...certainly better than the "sterile" sounding 49600/BUF634, but is much more difficult to implement than standard DIP-8 op-amps.
 
#37
^ How do any of these opamps have much of a sound outside of their circuit implementation? Within a composite, they all have silly low distortion potential and (ostensibly) enough drive power for most any reasonable headphone.
 
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